1. Field of the Invention
The present invention relates to a surround surveillance system for surveying surroundings of a mobile body. Specifically, the present invention relates to a surround surveillance apparatus for surveying surroundings of a mobile body for human and cargo transportation, such as a car, a train, etc.
2. Description of the Related Art
In recent years, an increase in traffic accidents has become a major social problem. In particular, in a place where a plurality of roads meet (T-intersection, crossroad, or the like), various accidents may sometimes occur. For example, people rush out into the street in which cars are travelling, a car collides head-on or into the rear of another car, etc. It is believed, in general, that such accidents are caused because a field of view for both drivers and pedestrians is limited in the crossroad area, and many of the drivers and pedestrians do not pay attention to their surroundings and cannot quickly recognize dangers. Thus, improvements in a car itself, arousal of attention of drivers, improvements and maintenance of traffic environments, etc., are highly demanded.
Conventionally, for the purpose of improving traffic environments, mirrors are installed at appropriate positions in a crossroad area such that drivers and pedestrians can see blind areas behind obstacles. However, the viewing range of a blind area which can be covered by a mirror is limited and, furthermore, a sufficient number of mirrors have not been installed.
In recent years, many large motor vehicles, such as buses and some passenger cars, have a surveillance system for checking the safety therearound, especially at a rear side of the vehicle. The system includes a surveillance camera installed in the rear of the vehicle, and a monitor provided near a driver's seat or on a dashboard. The monitor is connected to the surveillance camera via a cable. An image obtained by the surveillance camera is displayed on the monitor. However, even with such a surveillance system, the driver must check the safety of both sides of the vehicle manually using eyesight. Accordingly, in a crossroad area or the like, in which there are blind areas due to obstacles, the driver sometimes cannot quickly recognize dangers. Furthermore, a single camera of this type has a limited field of vision such that the camera can detect obstacles and anticipate collisions only in one direction. In order to check the presence/absence of obstacles and anticipate the danger of collision over a wide range, a certain manipulation, e.g., alteration of a camera angle, is required.
Since a primary purpose of the conventional surround surveillance system for motor vehicles is surveillance in one direction, a plurality of cameras are required for watching a 360° area around a motor vehicle; i.e., it is necessary to provide four or more cameras such that each of front, rear, left, and right sides of the vehicle is provided with at least one camera.
Furthermore, in the case where a vehicle is used in an area where or at a time when the environmental temperature is decreased to or below a certain temperature, such as areas of high altitude, areas of high latitude regions, during winter, etc., during a certain period after an engine of the vehicle is started, dew may sometimes be formed on a window glass of the vehicle, and subsequently frozen on the window. Such dew or frozen dew, or any other factor, may sometimes fog the window, causing difficulty for a driver to look outside from the inside of the vehicle. For example, when the driver parks the vehicle at the edge of a road, in many cases, the driver's vehicle is close to another vehicle or a person. When the driver starts to drive the vehicle under such circumstances, the driver of the vehicle cannot fully grasp the conditions around the vehicle unless the fog on the window of the glass is sufficiently wiped away or evaporated by warm air.
As a matter of course, in the case of using a motor vehicle, a driver encounters various situations where he/she is required to secure the safety around the motor vehicle. For example, when the driver starts to drive, the driver has to check the safety at the right, left, and rear sides of the motor vehicle, as well as the front side. Naturally, when the motor vehicle turns right or left, or when the driver parks the motor vehicle in a carport or drives the vehicle out of the carport, the driver has to check the safety around the motor vehicle. However, due to the shape and structure of the vehicle, there are blind spots/areas, i.e., areas that the driver cannot see directly behind and/or around the vehicle, and it is difficult for the driver to check the safety in such blind spots/areas. As a result, such blind areas impose a considerable burden on the driver.
Furthermore, in the case of using a conventional surround surveillance system, it is necessary to provide a plurality of cameras for checking the safety in a 360° area around the vehicle. In such a case, the driver has to selectively switch the cameras from one to another, and/or turn the direction of the selected camera according to circumstances, in order to check the safety around the vehicle. Such a manipulation is a considerable burden for the driver.
Furthermore, in the case where a window glass of a vehicle is fogged and it is difficult for a driver of the vehicle to see outside from the inside of the vehicle, the driver needs to increase the temperature inside the vehicle and wait until the fog on the window is cleared, or needs to wipe away the fog on the window so that the driver can check the safety around the vehicle manually using eyesight. In such a case, if there is means for helping the driver to check the safety around the vehicle instead of manually using eyesight, the driver can start the vehicle in a more secure manner.